1. Field of the Invention
The invention relates to a steering and safety linkage for a self-propelled walk behind mower.
2. Description of the Prior Art
Conventional wide area self-propelled walk behind mowers typically contain a front mower deck, nondriven front caster wheels, a power source such as an engine or motor, and two ground engaging rear wheels driven by the power source. The operator steers the mower by one of the driven rear wheels. For example, if a brake were applied to the left rear driven wheel or its drive were disengaged, the mower would change its direction of travel to the left, and would change its direction of travel to the right if a brake were applied to the right rear wheel or its drive were declutched. The operator applies the brake and/or clutch to the wheels by manipulating respective steering control levers mounted on the operator handles located at the rear of the mower.
A first type of conventional self propelled walk behind mower provides for the rear wheels to be engaged during operation unless the operator actuates one of the wheel control levers to declutch or brake the respective wheel. With this type of mower control, the operator walks behind the mower as it propels itself forward, and he engages the left or right steering lever when he desires to change the direction of travel. When one of the steering levers is engaged, its respective wheel is thereby caused to be declutched, or declutched and braked. The mower turns about the wheel being declutched and/or braked. Since the wheel drives are in a driving mode when the steering levers are released, the operator must lock them out of their engaged position by locking devices positioned on the operator handles near the steering levers in order to start the mower. Once the mower is started, the operator can then release the locks and gradually release the steering levers to initiate forward progress of the mower. To stop the progress of the mower the operator must engage both steering levers simultaneously, thereby braking both rear wheels. To park the mower, the operator applies the locking devices to the steering levers once they have been positioned in a declutched and/or braked configuration. The mower will then remain declutched and/or braked if the operator leaves the vehicle. If the operator were to start the mower without first applying the locking devices to the controls, the controls would be in their driven mode and the wheels would begin to proceed forward once started. Some mowers of this type are provided with an electrical starter switch that prevents the engine from being started while in a driving mode.
It is known to modify the above described mower by including a speed select lever between the operator handles that has a neutral setting and a plurality of driving speed settings. The speed select lever controls whether the shaft that transfers power to the wheels is in a neutral mode wherein the engine is not driving the shaft, or in a driven mode wherein the engine is driving the shaft via a set of gears. The operator places the speed selector in its neutral setting when starting the engine. To initiate forward movement of the mower, the operator shifts the speed selector to a setting corresponding to a desired speed. If the locking devices are engaged when the speed selector has been shifted, then the operator must disengage the locking devices and slowly release the wheel control levers to initiate forward movement. The operator depresses the respective wheel control lever during operation to execute a turn. In order to stop the mower's movement, the operator must either actuate both wheel control levers simultaneously or shift the speed selector to the neutral setting, which will allow the mower to coast to a stop. It is also known to include on such mowers an electrical switch mechanism that runs between the speed select lever and the engine that prevents the engine from being started when the speed select lever is not in the neutral position.
A second type of conventional mower provides a single transversely extending pivotable bar that controls the driving and braking of each rear wheel. As the operator pushes forward on the control bar the rear wheel drives are engaged and the mower moves forward. As the operator pulls back on the control bar, the wheel drives are declutched and then braked. When the operator pivots the left or right side of the bar backwardly, the corresponding rear wheel becomes disengaged while the other wheel continues to be driven to turn the mower about the disengaged wheel. As the operator pulls back further on that side of the bar, the corresponding wheel becomes braked and the mower executes an even sharper turn about that wheel. When the operator releases the bar, both wheels become disengaged and the mower coasts to a stop. To brake the mower, the operator must pull back on the bar. Therefore, the mower's drive is disengaged as the operator releases the control bar, but the brake is not simultaneously applied. To park the mower, the operator pulls back the bar, swings a brake lever forwardly and upwardly and wedges the brake lever against a stationary hand rest.